Card connectors are commonly used to receive a card, such as a memory card. Such known card connectors are roughly classified into either a type in which a card is directly inserted into a housing or a type in which a card is placed on a tray. The tray type card connector is commonly used because using a tray makes it possible to use an outer wall face of the tray as a part of an outer wall face of a device equipped with the card connector.
In recent years, cards, such as memory cards, are increasingly being downsized, and accordingly card connectors have become smaller and/or thinner. Therefore, trays are commonly being made of metal since used of a resin tray has insufficient strength.
When a card is inserted into a card connector having pads formed on the lower face thereof, the pads come into contact with contacts of the card connector creating an electrical connection between the card and the card connector. The minimal area and position of the pads formed on the lower face of the card are specified by a standard. Accordingly, in a card connector into which the memory card is inserted, contacts are so disposed as to come into contact with the pads, as long as the pads are formed to the standard. However, the standard of the card only specifies a minimal area of the pads, and allows the pads to have an area larger than or equal to the minimal area. According to the standard, a region on the lower face of the card (where the pads are not formed) is only a peripheral region that is only 0.2 mm wide from the edge. On the other hand, a tray has a large opening in the center thereof to bring contacts into contact with the pads on the lower face of the memory card, and has a shape in which only a region in the vicinity of the periphery of the lower face of the memory card is placed on the tray.
As mentioned above, a metal tray is used for strength. However, a short circuit may occur if the metal tray comes into contact with the pad and, therefore, according to the above standard, the memory card can be placed on the tray along the very narrow region, which is only 0.2 mm wide or less from the edge of the lower face of the memory card.
Placing the memory card on the tray is performed mostly by a user of the card connector (i.e. in a mobile device). The memory card easily falls through the central opening when the card placing region of the tray has a narrow width and, therefore, it is difficult to exactly place the memory card on the tray.
In this regard, since the opening of the tray is required for a portion of the minimal area specified by the standard, there is a suggestion that a region on which the memory card is placed is made wider, and a nonconductive portion is provided by applying an insulation coating to a region possibly coming into contact with the pads (as disclosed in U.S. Patent Application No. 2011/0255252).
Providing this nonconductive portion on the metal tray makes it possible to easily place the memory card on the tray, and prevents a short circuit between the metal tray and the pad.
However, providing the nonconductive portion on the metal tray as disclosed in the prior art causes an increase in cost, since the step of applying an insulation coating is added.